WEB4J is a Java web application framework.
It was built by the author of javapractices.com, out of frustration with other tools, which seem overly complex.
WEB4J follows a philosophy of deep simplicity and minimalism.

WEB4J is free and open source, with a BSD License.
You can download it here.
The web4j.com website provides good documentation, including some extensive examples of web apps built with WEB4J.